Behavioural genetics
Encyclopedia
Quantitative human behavioural genetics is a specialisation in the biological
field of behaviour genetics that studies the role of genetics
in human
behaviour employing quantitative-genetic
methods. The field is an overlap of quantitative genetics
and psychology
. Classically, human behavioural geneticists have studied the inheritance of behavioural traits.
published the first empirical work in human behavioural genetics, Hereditary Genius. Here, Galton intended to demonstrate that "a man's natural abilities are derived by inheritance, under exactly the same limitations as are the form and physical features of the whole organic world." Like most seminal work, he overstated his conclusions. His was a family study on the inheritance of giftedness and talent
. Galton was aware that resemblance among familial relatives can be a function of both shared inheritance and shared environments. Contemporary human behavioural quantitative genetics studies special populations such as twins
and adoptees
.
The initial impetus behind this research was to demonstrate that there were indeed genetic influences on human behaviour. In psychology, this phase lasted for the first half of the 20th century largely because of the overwhelming influence of behaviourism in the field. Later behavioural genetic research focused on quantitative methods.
which studies phenotypes such as schizophrenia
, bipolar disorder
, and alcoholism
.
Recent trends in behaviour genetics have indicated an additional focus toward researching the inheritance of human characteristics typically studied in developmental psychology
. For instance, a major focus in developmental psychology has been to characterize the influence of parenting styles on children. However, in most studies, genes are a confounding
variable. Because children share half of their alleles with each parent, any observed effects of parenting styles
could be effects of having many of the same alleles as a parent (e.g. harsh aggressive parenting styles have been found to correlate with similar aggressive child characteristics: is it the parenting or the genes?). Thus, behaviour genetics research is currently undertaking to distinguish the effects of the family environment from the effects of genes. This branch of behaviour genetics research is becoming more closely associated with mainstream developmental psychology
and the sub-field of developmental psychopathology
as it shifts its focus to the heritability of such factors as emotional self-control
, attachment, social functioning, aggressiveness, etc.
Several academic bodies exist to support behaviour genetic research, including the International Behavioural and Neural Genetics Society
, Behavior Genetics Association
, the International Society for Psychiatric Genetics
, and the International Society for Twin Studies
. Behaviour genetic work features prominently in several more general societies, for instance the International Behavioral Neuroscience Society
.
which disentangle genetic and environmental relatedness.
So, for instance, some researchers study adopted twins: the adoption study. In this case the adoption disentangles the genetic relatedness of the twins (either 50% or 100%) from their family environments. Likewise the classic twin study
contrasts the differences between identical twins
and fraternal twins within a family compared to differences observed between families. This core design can be extended: the so-called "extended twin study" which adds additional family members, increasing power and allowing new genetic and environmental relationships to be studied. Excellent examples of this model are the Virginia 20,000 and the QIMR twin studies.
Also possible are the "children of twins" design (holding maternal genetic contributions equal across children with paternal genetics and family environments; and the "virtual twins" design - unrelated children adopted into a family who are very close or identical in age to biological children or other adopted children in the family. While the classical twin study
has been criticized they continue to be of high utility. There are several dozen major studies ongoing, in countries as diverse as the USA, UK, Germany, France, the Netherlands
, and Australia, and the method is used widely in fields as diverse as dental caries
, BMI
, ageing
, substance abuse
, sexuality
, cognitive abilities
, personality
, values, and a wide range of psychiatric disorders. This is broad utility is reflected in several thousands of peer-review papers, and several dedicated societies and journals (See Twin study
).
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
field of behaviour genetics that studies the role of genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
in human
Human
Humans are the only living species in the Homo genus...
behaviour employing quantitative-genetic
Quantitative genetics
Quantitative genetics is the study of continuous traits and their underlying mechanisms. It is effectively an extension of simple Mendelian inheritance in that the combined effects of one or more genes and the environments in which they are expressed give rise to continuous distributions of...
methods. The field is an overlap of quantitative genetics
Quantitative genetics
Quantitative genetics is the study of continuous traits and their underlying mechanisms. It is effectively an extension of simple Mendelian inheritance in that the combined effects of one or more genes and the environments in which they are expressed give rise to continuous distributions of...
and psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
. Classically, human behavioural geneticists have studied the inheritance of behavioural traits.
History
In 1869, Francis GaltonFrancis Galton
Sir Francis Galton /ˈfrɑːnsɪs ˈgɔːltn̩/ FRS , cousin of Douglas Strutt Galton, half-cousin of Charles Darwin, was an English Victorian polymath: anthropologist, eugenicist, tropical explorer, geographer, inventor, meteorologist, proto-geneticist, psychometrician, and statistician...
published the first empirical work in human behavioural genetics, Hereditary Genius. Here, Galton intended to demonstrate that "a man's natural abilities are derived by inheritance, under exactly the same limitations as are the form and physical features of the whole organic world." Like most seminal work, he overstated his conclusions. His was a family study on the inheritance of giftedness and talent
Inheritance of intelligence
The study of the heritability of IQ investigates the relative importance of genetics and environment for variation in intelligence quotient in a population...
. Galton was aware that resemblance among familial relatives can be a function of both shared inheritance and shared environments. Contemporary human behavioural quantitative genetics studies special populations such as twins
Twin study
Twin studies help disentangle the relative importance of environmental and genetic influences on individual traits and behaviors. Twin research is considered a key tool in behavioral genetics and related fields...
and adoptees
Adoption
Adoption is a process whereby a person assumes the parenting for another and, in so doing, permanently transfers all rights and responsibilities from the original parent or parents...
.
The initial impetus behind this research was to demonstrate that there were indeed genetic influences on human behaviour. In psychology, this phase lasted for the first half of the 20th century largely because of the overwhelming influence of behaviourism in the field. Later behavioural genetic research focused on quantitative methods.
Contemporary behavioural quantitative genetics
Currently, the largest branch of human behavioural genetics is psychiatric geneticsPsychiatric genetics
Psychiatric genetics, a subfield of behavioral neurogenetics, studies the role of genetics in psychological conditions such as alcoholism, schizophrenia, bipolar disorder, and autism. The basic principle behind psychiatric genetics is that genetic polymorphisms, as indicated by linkage to e.g...
which studies phenotypes such as schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
, bipolar disorder
Bipolar disorder
Bipolar disorder or bipolar affective disorder, historically known as manic–depressive disorder, is a psychiatric diagnosis that describes a category of mood disorders defined by the presence of one or more episodes of abnormally elevated energy levels, cognition, and mood with or without one or...
, and alcoholism
Alcoholism
Alcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
.
Recent trends in behaviour genetics have indicated an additional focus toward researching the inheritance of human characteristics typically studied in developmental psychology
Developmental psychology
Developmental psychology, also known as human development, is the scientific study of systematic psychological changes, emotional changes, and perception changes that occur in human beings over the course of their life span. Originally concerned with infants and children, the field has expanded to...
. For instance, a major focus in developmental psychology has been to characterize the influence of parenting styles on children. However, in most studies, genes are a confounding
Confounding
In statistics, a confounding variable is an extraneous variable in a statistical model that correlates with both the dependent variable and the independent variable...
variable. Because children share half of their alleles with each parent, any observed effects of parenting styles
Parenting styles
A parenting style is a psychological construct representing standard strategies that parents use in their child rearing. There are many differing theories and opinions on the best ways to rear children, as well as differing levels of time and effort that parents are willing to invest.Many parents...
could be effects of having many of the same alleles as a parent (e.g. harsh aggressive parenting styles have been found to correlate with similar aggressive child characteristics: is it the parenting or the genes?). Thus, behaviour genetics research is currently undertaking to distinguish the effects of the family environment from the effects of genes. This branch of behaviour genetics research is becoming more closely associated with mainstream developmental psychology
Developmental psychology
Developmental psychology, also known as human development, is the scientific study of systematic psychological changes, emotional changes, and perception changes that occur in human beings over the course of their life span. Originally concerned with infants and children, the field has expanded to...
and the sub-field of developmental psychopathology
Developmental psychopathology
Developmental psychopathology is the study of the development of psychological disorders, such as psychopathy, autism, schizophrenia and depression, with a lifecourse perspective....
as it shifts its focus to the heritability of such factors as emotional self-control
Self control
Self control is the ability to control one's emotions, behavior and desires in order to obtain some reward later. In psychology it is sometimes called self-regulation...
, attachment, social functioning, aggressiveness, etc.
Several academic bodies exist to support behaviour genetic research, including the International Behavioural and Neural Genetics Society
International Behavioural and Neural Genetics Society
The International Behavioural and Neural Genetics Society was founded in 1996. The goal of IBANGS is "to promote the field of neurobehavioural genetics".- Mission :...
, Behavior Genetics Association
Behavior Genetics Association
The Behavior Genetics Association is a learned society that was established in 1970 and promotes research into the connection between heredity and behavior.- Aims :...
, the International Society for Psychiatric Genetics
International Society for Psychiatric Genetics
The International Society of Psychiatric Genetics is a learned society that aims to "promote and facilitate research in the genetics of psychiatric disorders, substance use disorders and allied traits". To this end, among other things, it organizes an annual "World Congress of Psychiatric Genetics"...
, and the International Society for Twin Studies
International Society for Twin Studies
The International Society for Twin Studies was founded in 1974, in Rome. It is a not-for-profit, multidisciplinary scientific organization...
. Behaviour genetic work features prominently in several more general societies, for instance the International Behavioral Neuroscience Society
International Behavioral Neuroscience Society
The International Behavioral Neuroscience Society , was founded in 1992. The goal of the IBNS is to "encourage research and education in the field of behavioral neuroscience". Its current president is D. Caroline Blanchard...
.
Methods of human behavioural genetics
Human behavioural geneticists use several designs to answer questions about the nature and mechanisms of genetic influences on behaviour. All of these designs are unified by being based around human relationshipsInterpersonal relationship
An interpersonal relationship is an association between two or more people that may range from fleeting to enduring. This association may be based on limerence, love, solidarity, regular business interactions, or some other type of social commitment. Interpersonal relationships are formed in the...
which disentangle genetic and environmental relatedness.
So, for instance, some researchers study adopted twins: the adoption study. In this case the adoption disentangles the genetic relatedness of the twins (either 50% or 100%) from their family environments. Likewise the classic twin study
Twin study
Twin studies help disentangle the relative importance of environmental and genetic influences on individual traits and behaviors. Twin research is considered a key tool in behavioral genetics and related fields...
contrasts the differences between identical twins
Twin
A twin is one of two offspring produced in the same pregnancy. Twins can either be monozygotic , meaning that they develop from one zygote that splits and forms two embryos, or dizygotic because they develop from two separate eggs that are fertilized by two separate sperm.In contrast, a fetus...
and fraternal twins within a family compared to differences observed between families. This core design can be extended: the so-called "extended twin study" which adds additional family members, increasing power and allowing new genetic and environmental relationships to be studied. Excellent examples of this model are the Virginia 20,000 and the QIMR twin studies.
Also possible are the "children of twins" design (holding maternal genetic contributions equal across children with paternal genetics and family environments; and the "virtual twins" design - unrelated children adopted into a family who are very close or identical in age to biological children or other adopted children in the family. While the classical twin study
Twin study
Twin studies help disentangle the relative importance of environmental and genetic influences on individual traits and behaviors. Twin research is considered a key tool in behavioral genetics and related fields...
has been criticized they continue to be of high utility. There are several dozen major studies ongoing, in countries as diverse as the USA, UK, Germany, France, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, and Australia, and the method is used widely in fields as diverse as dental caries
Dental caries
Dental caries, also known as tooth decay or a cavity, is an irreversible infection usually bacterial in origin that causes demineralization of the hard tissues and destruction of the organic matter of the tooth, usually by production of acid by hydrolysis of the food debris accumulated on the...
, BMI
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...
, ageing
Ageing
Ageing or aging is the accumulation of changes in a person over time. Ageing in humans refers to a multidimensional process of physical, psychological, and social change. Some dimensions of ageing grow and expand over time, while others decline...
, substance abuse
Substance abuse
A substance-related disorder is an umbrella term used to describe several different conditions associated with several different substances .A substance related disorder is a condition in which an individual uses or abuses a...
, sexuality
Human sexuality
Human sexuality is the awareness of gender differences, and the capacity to have erotic experiences and responses. Human sexuality can also be described as the way someone is sexually attracted to another person whether it is to opposite sexes , to the same sex , to either sexes , or not being...
, cognitive abilities
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
, personality
Personality type
Personality type refers to the psychological classification of different types of individuals. Personality types are sometimes distinguished from personality traits, with the latter embodying a smaller grouping of behavioral tendencies. Types are sometimes said to involve qualitative differences...
, values, and a wide range of psychiatric disorders. This is broad utility is reflected in several thousands of peer-review papers, and several dedicated societies and journals (See Twin study
Twin study
Twin studies help disentangle the relative importance of environmental and genetic influences on individual traits and behaviors. Twin research is considered a key tool in behavioral genetics and related fields...
).